374 COSMOS. 



the experiment made by the zealous astronomer Gautier M at 

 Geneva, in comparing four periods characterized by nume- 

 rous and by few spots on the Sun's disc (from 1827 to 1843), 

 with the mean temperatures presented by thirty- three European 

 and twenty-nine American stations of" similar latitude. This 

 comparison proves, by positive and negative differences, the 

 contrasts exhibited by opposite Atlantic coasts. The final 

 results, however, scarcely give 0*76 Fahr. as the cooling force 

 ascribed to the Sun's spots, and this might with rqual pro- 

 priety be attributed to errors of observation and the direction 

 of the winds at the localities indicated. 



It still remains for us to notice the third envelope of the Sun, 

 to which we have already referred. This is the most external 

 of the three ; inclosing the photosphere, is cloudy, and of 

 imperfect transparency. The remarkable phenomena of red, 

 mountain, or flame-like elevations, which, if not seen for 

 the first time, were at all events more distinctly visible during 

 the eclipse of the Sun of the 8th of July, 1842, when they 

 were simultaneously noticed by several of the most expe- 

 rienced observers, have led astronomers to assume the existence 

 of a third envelope of this kind. Arago, in a treatise devoted 

 to the subject, 17 has with much ingenuity tested the several 

 observations, and enumerated the grounds which necessitated 

 the adoption of this view. He has at the same time shown 



quotiens anona cara, qaotiens Lunse an Solis lumini caligo, 

 aut quid obstiterit." " The words of Cato in the fourth 

 book of his Origines are these : I may not write what is 

 frequently entered in the tables of the priests, that corn was 

 dear whenever there was any decrease in the light of the Sun 

 and Moon, or when anything obscured them." 



16 Gautier, Recherches relatives a I" influence que le nombre 

 des (aches snlaires exerce sur Ics temperatures terrestres, in 

 the Bibliotheque Universette de Geneve, Nouv. Serie, toni. li. 

 1844, pp. 327-335. 



17 Arago, in the Annuaire pour 1846, pp. 271-438. 



